Change of CD20 Expression in Diffuse Large B-Cell Lymphoma Treated with Rituximab, an Anti-CD20 Monoclonal Antibody: A Study of the Osaka Lymphoma Study Group oleh Naoki Wada, Masaharu Kohara, Hiroyasu Ogawa, Haruo Sugiyama, Shirou Fukuhara, Yoichi Tatsumi, Akihisa Kanamaru, Masayuki Hino, Yuzuru Kanakura, Eiichi Morii, Katsuyuki Aozasa